A Swiftly Tilting Planet is a Christian novel, but one that does not promote one denomination or theology. L'Engle is interested in exploring what it means to act is a Christian way, to follow the Golden Rule and actually become you brother and sister's keeper. Charles Wallace and Meg struggle not simply for self-preservation or for that of their immediate family, but for the survival of the human race and all life on the planet Earth. Unlike the earlier books in the series, the main characters have little self-knowledge to gain; they have already learned to give of themselves in previous encounters with the enemy.

Yet, despite its seemingly nontraditional perspective, A Swiftly Tilting Planet is a book that explores the essential nature of Christian behavior.

Some adult readers may find L'Engle's examination of the nature of Christianity overly imaginative in its use of preChristian mythology...